Computing systems comprising computer devices connected by data communications networks increasingly are growing in scale to meet consumer demand. In large-scale computing systems, computer devices and associated cabling and hardware may be located in large computer rooms and data centers in specially designed storage cabinets or racks that allow access thereto by operators, such as maintenance staff. The arrangement of storage cabinets in a computer room may be based on a number of design considerations. Such considerations include: topology design relating to the overall use of space within the room; general infrastructure design relating to the arrangement of mechanical systems (e.g., cooling systems) and electrical systems (e.g., power systems) within the room, and technology infrastructure design relating to the arrangement of the computer systems hardware, communications network cabling etc., within the room.
Typically, computer rooms arrange storage cabinets in rows, in which pairs of rows of storage cabinets are arranged with their fronts facing opposite each other with an aisle in between, to allow for access by maintenance staff, as shown in FIG. 1A which is a schematic diagram of an arrangement of part of a computing system in a computer room showing an example technology infrastructure design. One such design concept that may be used in data centers is the so-called “hot aisle/cold aisle layout”, which comprises rows of storage cabinets spaced by alternate “hot aisles” and “cold aisles”, as shown in FIG. 1B which is schematic diagram of an arrangement of part of a computing system in a computer room showing an example general infrastructure design. In FIG. 1B, the fronts of rows of cabinets face into a cold aisle and the backs of rows of cabinets face into a hot aisle. A cooling system is arranged to control the flow of air around the cabinets for heat dissipation, so as to prevent overheating. In particular, the cooling system may be arranged to provide cold air into the fronts of the cabinets, and thus in front of the computing devices in the cabinets, via the “cold aisles”. For example, as shown in FIG. 1B, cold air may flow from the floor of the cold aisles and into the fronts of the adjacent rows of cabinets as shown by arrows shaded as “cold air”. The cooling system is further arranged to extract hot air, which is vented, for example by fans in the computing devices, from the backs of the rows of cabinets via the “hot aisles”. For example, as shown in FIG. 1B, hot air may flow in a direction towards one end of the rows as shown by arrows shaded as “hot air”.
In practice, when storage cabinets for computer devices are arranged in rows, the computer devices in each row of cabinets are connected to the same communications cabling, and thus part of the same system network. However, it is not usually possible to provide cabling between adjacent rows of cabinets, for practical reasons and/or design considerations, and so computer devices in adjacent rows of cabinets are typically connected to different network segments of the system network.
Computer systems require continuing management for maintenance and to remedy faults giving rise to operational and/or performance errors. For this purpose, individual computer devices, such as servers, may include “diagnostic tools”, typically comprising automated diagnostic monitoring, which may identify errors or events based on diagnostic information. An identified error or event may be indicated to an operator, for example by means of a display on the front panel of the computer device. For instance, a particular light, such as an indicator LED, on the front panel of the computer device may be lit in particular manner to indicate a certain type of error.
In addition, more advanced diagnostic tools may report identified errors in computer devices as “events” to a local or remote management apparatus or console, by sending management data, for example as an “event message” including associated error and diagnostic information, over a management network. In particular, a so-called Advanced System Management module (also known as System Management Interface) may be provided in each computer device (e.g., server) for diagnostic monitoring and reporting using proprietary communications and messaging formats. Such advanced diagnostic monitoring enables a fault or other problem to be identified by an operator of a management device or console at a remote location, and, in some cases, may allow for the fault or problem to be fixed or otherwise resolved remotely. In order to provide such advanced diagnostic functionality, each computer device needs to be able to connect to a management network for reporting events to the management console. However, if a fault exists in the connection of a computer device to the system network, the computer device is unable to connect to the management network via the system network. In order to address this issue, conventional network configurations provide a second system network to provide redundancy (hereinafter called “redundant network”), as shown in FIG. 2A and described below. In this way, if a computer device is unable to connect to the system network, the computer device is able to report the fault as an event over the redundant network to the management console.
FIG. 2A shows a conventional network configuration for a part of the computing system of FIGS. 1A and 1B. FIG. 2A comprises computer devices of a first row 12, computer devices of a second row 14, and aisle 16 between the first row 12 and the second row 14, where the computer devices are depicted as servers. Each server of the first row 12 is connected to a first network switch X for the network segment of the system network (shown in solid line in FIG. 2A). In addition, each server of the first row 12 is connected to a second network switch Y, providing a redundant network (shown in dashed line in FIG. 2A). Similarly, each server of the second row 14 is connected to corresponding first and second network switches X and Y associated with the system network and the redundant network, respectively. Thus, as shown in FIG. 2A, the provision of a redundant network requires an additional network switch Y for each segment and additional cabling to each computer device, which may clutter the storage cabinets in each row, increase energy consumption and reduce heat dissipation, as well as increase infrastructure costs. In FIG. 2A, the first and second network switches X and Y are connected to a management console 70 via a system network 65.